The discovery of the remarkable antibiotic properties of penicillin stimulated great interest in this field which has resulted in the finding of many other valuable antibiotic substances such as other penicillins, cephalosporins, streptomycin, bacitracin, tetracyclines, chloramphenicol, erythromycins and the like. In general, the antibacterial activity of each of these antibiotics does not include certain clinically important pathogenic bacteria. For example, some are principally active against only gram-positive types of bacteria. Furthermore, acquired resistance over the course of widespread use of existing antibiotics in the treatment of bacterial infection has caused a serious resistance problem to arise.
Accordingly, the deficiencies of the known antibiotics have stimulated further research to find other antibiotics which will be active against a wider range of pathogens as well as resistant strains of particular microorganisms.